When Twilight goes to Canterlot for Princess training, she lives Spike with Rainbow Dash for the day along with Pinkie Pie who's having a sleepover with Rainbow Dash. That night, Rainbow Dash and Pinkie Pie play pranks on Spike and warn him that on midnight, ghosts appear. But when Spike goes to sleep, Rainbow Dash and Pinkie Pie get a visit from the spirit of a duck whom they pulled a prank on earlier...when it's actually Daffy Duck messing with them.
Special thanks to GunsNRoses365 (Author of A Mothers Love) for helping me out on this story.